Wrapped pencil-shaped articles and method of making same



Feb. 14, 1956 J. J. CLANCY ET AL 2,734,838

WRAPPED PENCIL-SHAPED ARTICLES AND METHOD OF MAKING SAME Filed Oct. 19 1951 INVENTORS JOHN J. CZAA/cY DflV/D VI./ 401/ I United States Patent WRAPPED PENCIL-SHAPED ARTECLES AND METHOD 0F MAKING SAME John J. Clancy, Westwoed, and David W. Levering, eedham, Mass, assignors to Arthur D. Littie, Zine, Sambridge, Mass a corporation of Massachusetts Application October 19, 1951, Serial No. 252,171 7 Claims. (Cl. 154-453) This invention relates to the manufacture of wrapped pencils and pencil-like articles, and more particularly to the manufacture of pencils and pencil-like articles Whose sheaths are prepared from paper.

Because the supply of cedar wood suitable for pencil manufacturers is no longer obtainable in unlimited quantities, and is becoming increasingly expensive, attention has been directed to the manufacture of pencils by sheathing the pencil lead with alternative materials. In place of cedar Wood, other woods have been substituted but these are generally conceded to be inferior to cedar. Attempts have also been made to prepare wrapped paper sheaths by laminating paper with various adhesives such as sodium silicate and thermosetting resins alone. The pencils made from sodium silicate have proved unsatisfactory when kept for long storage periods because they are sensitive to climatic changes, particularly humidity, and are difiicult to sharpen under high humidity conditions.

An object of this invention is to make composition pencils and pencil-like articles which will have the characteristic qualities generally associated with high-grade wood pencils such as strength, good sharpening, both by knife and by conventional pencil Sharpeners, and high resistance to humidity.

Another object of this invention is to produce pencils from inexpensive and readily available materials.

Still another object is to produce pencils by a simple mechanical operation.

These and other objects which will become apparent may be accomplished by the procedure of the present 'invention, which is described 'below.

Briefly the process of making our pencils and pencil-like articles comprises enveloping a core with paper which has been coated or impregnated with a binder, shaping the resulting sheath if desired, and curing the binder. The articles may then be finished in the conventional manner by lacquering, stamping, applying fermles, etc.

The binder consists of the reaction product of an ad hesive and an embrittling agent and, if desired, a lubricant, a perfume. and coloring material. It must be stable toward humidity changes so that the resulting impregnated or coated sheath retains its physical properties over extensive temperature and humidity ranges.

The preferred adhesive is starch, or a product resulting from the degradation of starch, such as dextrine. Other water colloidally soluble relatively high molecular weight polyhydroxy compounds including vegetable gums, such as gum acacia, and pectin, also are satisfactory adhesives. Polyvinyl alcohol may also be employed. Some polyhydroxy compounds, such as starches and starch derivatives, are better suited than others because of their solubility characteristics, their initial tack and adhesive qualities, but any water colloidally soluble starch, or starch hydrolysates, may be employed if desired.

The embrittling agent serves to lessen the toughness of the adhesive and that section of paper coming in contact with the embrittling agent. This makes the formed sheath cut more readily and cleanly by the shearing forces of a pencil sharpener or knife. While water colloidally soluble materials, which upon heating react with the adhesive and become converted into an insoluble form, are generally satisfactory, and the low molecular weight formaldehyde condensates, such as those with phenol, furfury-l alcohol, urea, and melamine, and combinations of these, are typical examples of useful and preferred thermosetting resins or embrittling agents, dimethylolurea has been found to be a most desirable thermosetting or embrittling agent. These water colloidally soluble materials also serve to render the composition less sensitive to humidity after reaction.

The embrittling agent is referred to above as a thermosetting resin. The term thermosetting resin is intended to embrace materials such as dimethylolurea which upon heating alone polymerizes to form a resin. In the present invention they also react with the adhesive to form the binder for the pencil sheath.

The adhesive must be tacky enough to hold the paper or pulp including the final lap, in the case of a paper sheet, during and after the Wrapping operation.

The lubricant may advantageously be calcium stearate or similar soap-like material. Waxes, preferably in the form of emulsions, may also be employed, as well as unctuous minerals such as talc.

Many types of paper are suitable for this invention, but it is preferable to use a paper similar to newsprint. it is desirable to incorporate some kraft, or sulfite fiber, in the paper when it is being made to give it additional strength.

The following description of the process, using the preferred materials, is as follows:

The binder comprised of a dextrine, such as tapioca dextrine as the adhesive, and dimethylolurea as the embrittling and stabilizing agent, is made up as a watersolution in equal parts and contains a small amount of dispersed calcium stearate as a lubricant. The concentration of materials in solution is not critical but should be as high as possible so that less water need be removed from the wrapped pencil. The concentration should ,be such as to give suficient tack to .the surface of the treated paper to preclude unwinding or delaminating after forming and before drying.

The binder solution is impregnated or coated on the paper. Although it is usually preferable to add the adhesive and the embrittling agent "to the paper in one solution as a one-step process, it is possible first to treat the paper with the embrittling agent .and then to Wrap the paper with adhesive into the desired pencil. The quantity of binder required for this operation may vary from 10 to 50% by weight of the paper and preferably 20-35% by weight.

Forming the pencil may be accomplished by rolling the pencil lead up in treated paper until the desired size .is reached, shaping the pencil as by putting it through a die to give it a hexagonal shape, drying the pencil either by heat or otherwise and with or without a catalyst for the reaction, and finishing, if desired, in the conventional manner. Economic advantages may be obtained by coating the tab end of the wrapping paper with a plastic or other finishing material so that the finished article. will have the tab on its outer surface, thus eliminating the necessity for lacquering.

The application of the binding material and the rolling of the pencil may be done over a wide temperature range. It is preferable, however, to carry out the wrapping operation at from -160 F. These temperatures allow the use of higher concentration binders and the pencil results in being introduced into the drying chamber already preheated. The drying temperature is also not criticalthe maximum temperature allowable being dependent upon the paper used and the temperature at which it deteriorates, but the preferred temperature range is from 180 to 275 F. The length of the drying cycle depends upon the paper and temperature used and is usually about 4 hours at 212 F., if no catalysts are used. The time may be shortened by use of catalysts, for instance diammonium hydrogen phosphate.

In the above description it was stated that the ratio of dextrine to dimethylolurea is preferably kept at approximately one to one by weight. However, it has been found satisfactory to use up to '7 parts by weight of dextrine to 3 parts by weight of dimethylolurea. A larger proportion of dextrine tends to make the resulting pencil sensitive to high humidity. On the other hand, it is possible to increase the proportion of dimethylolurea to a ratio of 1 part by weight of dextrine to 9 parts by weight of dimethylolurea. Larger proportions of dimethylolurea do not permit proper adhesion particularly with respect to the final lap. As a matter of fact, substantially higher proportions of dimethylolurea may make the present simple wrapping process impractical, since the individual pencils would have to be held mechanically until the dimethylolurea was set to eliminate unwrapping.

The invention may be better understood by reference to the accompanying drawing wherein:

Fig. l is a coated paper, a pencil lead and a ferrule.

Fig. 2 is a partially rolled-up pencil.

Fig. 3 is a rolled-up pencil.

Fig. 4 is the pencil of Fig. 3 after passing through a die to form it into a hexagonal shape.

Fig. 5 is the pencil of Fig. 4 complete with ferrule and sharpened.

Fig. 6 is an eraser surrounded by a sheath similar to that of the pencil lead in Fig. 5.

Referring to the drawings more specifically, 11 is the base, such as paper, coated with a binder 12. Pencil lead is rolled up in the coated base to form a blank pencil having a nearly invisible lap 16. After passing pencil blank through a hexing die, ferrule 13 having an eraser 14 is attached. A lacquer 17 is applied to pencil 15. Fig. 6 refers specifically to an eraser having a sheath 18 and an abrasive composition 19 located centrally within the sheath 18.

In order to more fully understand the invention, the following examples, illustrative of successful methods of accomplishing the objects above stated, are given:

Example I Tapioca dextrine 72.5 Dimethylolurea (60% solids) 121.0 Water 56.5 Calcium stearate 2.5

Example II Kraft paper was impregnated with a solution of dimethylolurea to give a pickup of 10% solids on the weight of the paper. The treated sheet was dried and then wrapped in an adhesive bath having the following composition:

Parts Potato starch 50 Water 50 Microcrystalline wax 5 The starch and water were heated to 160 F. to produce a smooth dispersion. After cooling to 100 F., the wax was added with stirring as a water dispersion. The resulting pencil was heated at 212 F. until dry. Sharpening characteristics were similar to those of cedar pencils and showed good resistance to high humidity.

Example III G. Polyvinyl alcohol 10.0 Dimethylolurea solids) 66.7 Water 23.3

The polyvinyl alcohol was dissolved in the water and the dimethylolurea added. Pencils were made in the manner described in Example'l using the same paper with the above binder composition at a temperature of F. The resulting pencils were resistant to high humidity and had good sharpening characteristics.

Example IV G. Gum acacia 10.0 Dimethylolurea (60% solids) 66.7 Water 23.3

The acacia gum was dissolved in the water followed by addition of the dimethylolurea with stirring. Cores of rubber eraser material were wrapped with newsprint coated with the above binder composition and the article was dried at 212 F. The resulting assemblies are resistant to high humidity and the sheath sharpened easily and cleanly to expose a new surface.

Example V Tapioca dextriue 5.0 Dimethylolurea (60% solids) 75.0 Water 20.0 Calcium stearate 1.0

Example V1 G. Apple pectin Q 10.0 Water 125.0 Dimethylolurea 16.7

The pectin was first dissolved in water with heating after which the dimethylolurea was added with stirring. Pencils were made from the above composition by coating the modified newsprint paper, drying, remoistening and wrapping in the manner described in Example I. The resulting pencils were resistant to high humidity and had good sharpening characteristics. a

In the foregoing description, reference was made to the binder comprising an adhesive and an embrittling agent. The heating of the embrittling agent causes a polymerization reaction to take place. It is believed that the adhesive enters into this polymerization reaction since a product is formed from which the water soluble adhesive may not be extracted. In compatible systems such as the dimethylolurea-dextrine mixtures X-ray diffraction studies disclose that both the adhesive and embrittling agent when polymerized alone have a definite crystal structure. When heated together, the final prodnet is amorphous. It is known that by using an embrittling agent, the sheath may be readily sharpened, either by knife or by mechanical means, to form a smooth cut similar, or superior, to that obtained by the finest straight grained pencil wood.

Reference is made herein to vegetable gums. This is intended to include not only materials such as gum acacia, but also in its broader sense to include water colloidally soluble materials such as pectin, starch, and hydrolysates of starch such as dextrine.

Extensive laboratory tests have shown that pencils made in accordance with the process herein described are strong, and have superior sharpening qualifies as well as being relatively insensitive to humidity changes.

If it is desired, the paper used in wrapping the pencil may be dyed and perfumed a color and odor similar to that of cedar wood. When so treated, it is difiicult to distinguish a pencil made in accordance with this invention from that made from prime cedar wood.

Although the above examples and description have been directed primarily to pencils, it is apparent that this invention is equally applicable to pencil-like articles such as crayons, erasers, eyebrow pencils, and similar structures. The appended claims are therefore intended to cover broadly such articles.

Having now described our invention, we claim:

1. As an article of manufacture, a core, and a rigid sheath surrounding said core, said sheath comprising paper tightly wound upon said core, and bonded together and to said core by a binder and heat cured at a temperature between ambient and about 275 F., said binder preventing delamination and consisting essentially of dimethylol urea and a high molecular weight water colloidally soluble polyhydroxy compound selected from the group consisting of starch, hydrolysates of starch, dextrine, pectin, gum acacia, and polyvinyl alcohol, said polyhydroxy compound and said dimethylol urea being present in a weight ratio of between 7:3 and 1:9, said sheath being substantially unaifected by humidity.

2. An article of manufacture in accordance with claim 1, wherein said polyhydroxy compound is starch.

3. An article of manufacture in accordance with claim 1, wherein said polyhydroxy compound is dextrine.

4. An article of manufacture in accordance with claim 1, wherein said polyhydroxy compound is pectin.

5. An article of manufacture in accordance with claim 1, wherein said polyhydroxy compound is polyvinyl a1- cohol.

6. An article of manufacture in accordance with claim 1, wherein said binder contains a lubricant.

7. The process of forming a rigid sheath about a core, which comprises applying to a paper sheet a binder consisting essentially of dimethylol urea and a water colloidally soluble, relatively high molecular weight, polyhydroxy compound selected from the group consisting of starch, hydrolysates of starch, dextrine, pectin, gum acacia, and polyvinyl alcohol, in a weight ratio of between 3 :7 and 9: 1, respectively, wrapping the thus-treated paper tightly around said core to form said sheath thereabout, and heating the resulting structure at a temperature between ambient and about 275 F. sutficient to cause said polyhydroxy compound and said dimethylol urea to form a reaction product which is substantially unafiected by humidity and which bonds the convolutions of said sheath firmly together against delamination and which also bonds said sheath to said core.

References Cited in the file of this patent UNITED STATES PATENTS 444,233 Denney Ian. 6, 1891 477,593 Greenfield June 21, 1892 600,745 Sands Mar. 15, 1898 679,264 Pedley July 23, 1901 1,222,152 Smith Apr. 10, 1917 2,121,076 Ellis June 21, 1938 2,302,309 Glarum et al Nov. 17, 1942 2,510,941 Ake et a1. June 13, 1950 FOREIGN PATENTS 16,194 Great Britain of 1898 

1. AS AN ARTICLE OF MANUFACTURE, CORE, AND A RIGID SHEATH SURROUNDING SAID CORE, SAID SHEATH COMPRISING PAPER TIGHTLY WOUND UPON SAID CORE, AND BONDED TOGETHER AND TO SAID CORE BY A BINDER AND HEAT CURED AT A TEMPERATURE BETWEEN AMBIENT AND ABOUT 275* F., SAID BINDER PREVENTING DELAMINATION AND COMSISTING ESSENTIALLY OF DIMETHYLOL UREA AND A HIGH MOLECULAR WEIGHT WATER COLLOIDALLY SOLUBLE POLYHYDROXY COMPOUND SELECTED FROM THE GROUP CONSISTING OF STARCH, HYDROLYSATES OF STARCH, DEXTRINE, PECTIN, GUM ACACIA, AND POLYVINYL ALCOHOL, SAID POLYHYDROXY COMPOUND AND SAID DIMETHYLOL ALCOHOL, SAID PRESENT IN A WEIGHT RATIO OF BETWEEN 7:3 AND 1:9, SAID SHEATH BEING SUBSTANTIALLY UNAFFECTED BY HUMIDITY.
 7. THE PROCESS OF FORMING A RIGID SHEATH ABOUT A CORE, WHICH COMPRISES APPLYING TO A PAPER SHEET A BINDER CONSISTING ESSENTIALLY OF DIMETHYLOL UREA AND A WATER COLLOIDALLY SOLUBLE, RELATIVELY HIGH MOLECULAR WEIGHT, POLYHYDROXY COMPOUND SELECTED FROM THE GROUP CONSISTING OF STARCH, HYDROLYSATES OF STARCH, DEXTRINE, PECTIN, GUM ACACIA, AND POLYVINYL ALCOHOL, IN A WEIGHT RATIO OF BETWEEN 3:7 AND 9:1, RESPECTIVELY, WRAPPING THE THUS-TREATED PAPER TIGHTLY AROUND SAID CORE TO FORM SAID SHEATH THEREABOUT, AND HEATING THE RESULTING STRUCTURE AT A TEMPERATURE BETWEEN AMBIENT AND ABOUT 275* F. SUFFICIENT TO CAUSE SAID POLYHYDROXY COMPOUND AND SAID DIMETHYLOL UREA TO FORM A REACTION PRODUCT WHICH IS SUBSTANTIALLY UNAFFECTED BY HUMIDITY AND WHICH BONDS THE CONVOLUTIONS OF SAID SHEATH FIRMLY TOGETHER AGAINST DELAMINATION AND WHICH ALSO BONDS SAID SHEATH TO SAID CORE. 